Robert Kubica has conceded his Formula 1 comeback is a story “nobody has believed” during his battle to return to the sport after his rallying crash.

The Polish driver has been officially announced as a Williams F1 race driver for 2019 alongside the already-announced George Russell to complete his incredible comeback from a partially-severed right forearm suffered in a rallying accident in early 2011.

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Kubica had been set to race for Renault that year before his life-threatening rally crash, and duly left F1 circles during his injury comeback, initially in rallying between 2013-2016 before targeting his F1 return.

The Grand Prix winner is adamant his physical limitations, where he uses the steering wheel at “70% with his left hand”, won’t restrain his speed on his F1 race comeback and was always confident of returning even through doubts from outsiders.

“From a human point of view, I understand and I see the point that it’s a story which probably nobody has believed,” Kubica said. “The only one who probably never gave up was myself and people who were around me, who I’d like to thank them. But we all knew that it might be something not achievable. This day shows that somehow nothing is impossible.

“Of course a lot of things had to come together and a lot of work has been included, not only from my side, to be here.

“But from driving point of view, the point is very simple. You don’t need to wait too much and you will see! I think if I will not be able to drive competitively fast, I will not be here.

“This is I think more and more the way of thinking that people see my limitations and they are asking how it’s possible I can do it.”

Kubica first drove a current specification F1 car with Renault during the Hungary in-season test in 2017 but was turned down by the French manufacturer before joining up with Williams.

The Pole had been in a prime position for a 2018 race seat at the British squad, only to be ultimately overlooked in favour of Sergey Sirotkin this season, but has been able to convince the team in his reserve and test driver role this year.

Kubica feels the extra time inside the F1 team has been invaluable to improve his sharpness and preparation ahead of his comeback.

“I know it’s hard to believe but I think Williams have seen it this year and I have seen it in the last 16 months, or 18 months, since I first drove an F1 car in Valencia last year,” he said. “I can do it thanks to hard work but also my limitations are not limiting myself as most people are thinking.”